Method of making spline couplings



April 25, 1933. J, EDGAR METHOD OF MAKING SPLINE COUPLINGS Filed Aug. 5, 1931 3 Sheets-Sheet 1 INVENTOR John Edgar ATTORNEYS April 25, 1933.

J. EDGAR METHOD OF MAKING SPLINE COUPLINGS I Filed Aug. 3, 1931 3 Sheets-Sheet 2 1 7 -75 3' W h W" INVENTOR John Edgar BY M M M ATTORNEYS April 25, 1933.

J. EDGAR METHOD OF MAKING SPLi NE COUPLINGS 3 Sheets-Sheet 3 Filed Aug. 3, 1,931

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INVENTOR John Edgar BY ATTORNEY 5 Patented Apr. 25, 1933 UNITED STATES PATENT OFFICE JOHN EDGAR, 0F nooxroan, ILLINOIS, ASSIGNOR To BARBER-0013M coinrANY, or nocxroan, ILLINOIS, A CORPORATION OF ILLINOIS METHOD OF MAKING SPLINE COUPLINGS Application filed August a, 1931. Serial No. 554,645.

The present invention relates to a new method of making spline couplings adapted for example to secure an outside member, such as the hub of a gear, to an inside member, such as a shaft, and has particular reference to the forming of a spline shaft having parallel integral keys with tapered bases.

The primary object of the present invention resides in the provision of a novel method of generating keys of the foregoing character on the inside member or spline shaft of aspline coupling.

Other objects reside in the provision of a novel method of hobbing the inside member of a spline coupling with parallel integral keys having tapered bases which results in accurate forming and spacing of the keys, whichmakes possible forming of the tapered bases without interference regardless of the varying radius along the taper, which pro-- duces bases or roots for the keys that are concentric in cross-section to the axis, and which permits of a high rate of production.

Still another object is to provide a new and improved method in which a given hob may be used togenerate keys with tapered bases on shaft sections of different lengths and degrees of taper.

A further object resides in the provision ofa novel method of bobbing rotary members with peripheral projections or keys uniformly spaced about the axis of rotation and extending generally longitudinally of the axis, which method comprises feeding the member and a suitable hob other through cutting engagement along a path inclined to the hole axis and also inclined to a normal to said axis of rotation, so as to project the general longitudinal form of the hob along said path to provide a foreshortened form on the keys and the intervening spaces, generally along said axis of rotation. 1 p I The invention is illustrated in connection with the accompanying drawings, in which:

Figure 1 is a perspective view of a singlethread hob in operative relation to the work shortly after the beginning of the cutting operation. J

.ticular spline coupling,

relatively to each- Fig. 2 is a vertical axial sectional view of the hob in operative relation to the work.

Fig. 3 is a fragmentary perspective view of one end of the finished inside member.

Fig. 4 is a diagrammatic view illustrating the method employed in splining the inside member.

Fig. 5 is a diagrammatic representation in four fragmentary views of successive stages in the generating action.

Fig. 6 is a view similar to Fig. 4 but illustrating the use of a multiple-thread hob.

While the invention in its broad aspects is not limited to the specific details of any parin connection with a coupling comprising an inside member in the form of a shaft 10. The end of the shaft .10 is formed with a reduced threaded extension or stud 11 adapted to receive a suitable nut (not shown). Formed integrally with the end of the shaft 10 are a plurality of generally longitudinal generated spline keys 12 separated by interdental spaces 13. The keys 12 are parallel, that is to say, the outer longitudinal edges are parallel. The sides of each key 12 are parallel, and hence the sides 'of each space 13 converge laterally and inwardly. Preferably, the keys 12 are formed in uniformly spaced relation about the shaft 10.

The roots a of the spaces 13 are tapered longitudinally'of the tapered or conical base for the keys 12. Ob viously, due to the taper, the side edges 6 of the root a and also the sides of each space 13 converge longitudinally. The roots 0 in .CIOSS-SGCtlOIl are arcuate, and concentric to the axis of the shaft 10. Preferably, clearance grooves 14 are formed in the spaces 13 at the longitudinal margin of the roots 0;. The present invention is not directed to the method of forming the outside member of the spline coupling, and hence the latter is not shown. It is suflicient to say that any suitable outside member (not shown) adapted to receive the splinedsection of the shaft 10 and having keyways and projections adapted tointerfit with the keys 12 and keyways 13 and to seat snugly on the. roots or may be provided.

it is herein described shaft 10 to form a Y The keys 12 and roots .1 are produced by a generating or hobbing method which ma es possible the formation of the keys 12 integral with the-shaft 10 without encountering interference even though the roots at of the spaces 13 converge in width along the taper, and obviously makes possible a high rate of roduction. Generated keys are correctly ormed and accurately spaced even though the radius of the roots a of the spaces changes along the taper.

In carrying out the method, a special hob 15 is used. The hob 15 has a cylindrical body 16 formed with the usual axial bore 17, and may have any suitable number of threads 18. Preferably, the hob 15 is of the single-thread type shown in Figs. 1, 2, 4: and

.5. However, a multiple-thread hob, for example one with three threads 18 shown in 2 Fig. 6 may be used. Generally longitudinal .fiutes or gashes 19 formed in the body 16 and preferably inclined into perpendicular relation to the threador threads 18 intersect the latter to form teeth 20 having relieved tops 0. In either form of hob, each thread 18 is tapered from one end to the other of the body 16. It will be noted that the taper progresses both along the thread and longitudinally of the hob in an axial plane, and'that the tops (I of the hob teeth are therefore laterally inclined in accordance with the axial taper. .In effect, a tapered hob with the tops 0 ofthe teeth 20 laterally inclined in any axial plane at an angle d (Fig. 2) is thus 'rovided. Preferably, ribs or lugs 21 are ormed on the hob teeth 20, to cut the clearance grooves 14. For cutting aspline shaft without the clearance groove 14, a hob similar to the hob 15 but with the lugs 21 removed would be used.

It will be understood that the hob thread or threads 18 may have any desired contour depending on the form to be generated on the keys 12, and that in the resent instance, the thread contour is such tl fat straight parallel sides will be formed on each key, and the rootsa of .the spaces 13 will be concentric to the axis of the shaft 10. p

In carryingout the method, the hob 15 is positioned into operative relation withthe end of a solid uncut shaft 10, as illustrated in full outline in Fi 6.- In so positioning the hob 15, it is-a justed angularly to ocate each thread 18 parallel to the keys 12 to be cut, and preferably is located initially off the end and at one side of the shaft 10, with the large end of the hob the leading end.

The angular position of the hob 15 depends on the thread angle. For a single thread hob 15 (see Fig. 4), the angle e subtended with the shaft 10 is relatively large. When using a triple-thread hob 15, as illustrated in Fig. 6, due to the increased thread angle, the angle e subtended with the shaft is correspondingly smaller. Except for the difference in angular position,'the two hobs are positioned relative to the work in the same manner.

In operation, with a hob 15, either singlethread or. multiple-thread, having the foregoing specifications and the correct position,

the hob 15 and the shaft blank 10 are rotated in timed relation. In the course of this timed rotation, the hob 15 is gradually fed relatively across the shaft in a diagonal direction indicated by the arrow 11. through cutting engagement into the position indicated in dotted outline in Fig. 6. The direction of cross feed is variable depending on the length 7 of the shaft section to be splined. The initial position of the hob is determined in part by the direction of cross component along the arrow 72. is constant in speed, ,-and the longitudinal feed component along the arrow 11 is variable to obtain thedesired resultant.

The diagonal cross feed effects a rolling or generating action by reason of which the keys 12 and the roots a of the spaces 13 are correctly and accurately formed, and which avoids interference even though the roots of the s aces are tapered, and hence variable in widt and radius along the taper. The generating action is illustrated in Fig. 5. As the hob axis gradually crosses the axis of the shaft on a diagonal line, the spaces 13 are cut to full depth progressively from the outer end to the inner end of the shaft section f. By reason of the taper of the hob, the roots of the spaces are tapered. The lugs 21 on the hob 15 cut the grooves 14. The edges 6 are not generated with sharp corners, but by reason of the grooves 14, projections on the outside member (not shown) adapted to interfit with the keys 12 and to seat snugly on the tapered roots a can be formed with sharp outer longitudinal 12 are uniform in width, and the roots a of the spaces 13 are tapered as described. The invention in its broad aspects is not limited to the specific form of the hob thread since various forms may be used to produce different kinds of keys 12 and spaces 13.

I claim as my invention:

1. The method of hobbing. a spline shaft sectioncomprising rotating the section and a hob having a longitudinally tapered thread in timed relation, with the hob inclined longitudinally moving the hob relatively across the section along a diagonal line inclined to the hob axis during said rotation through cutting engagement.

2. The method of hobbing a rotary member with straight longitudinal teeth comprising rotating the member and a hob in timed relation, with the hob inclined longitudinally to the axis of the member, and moving the hob relatively across the member along a diagonal line extending obliquely across the axis of the member during said rotation through cutting engagement.

3. The method of bobbin-g the inside member of a spline coupling which comprises positioning the member and hob in operative relation, with the hob inclined longitudinally to the member and initially located oil the end and at one side of the member, rotating the member and the hob in timed relation, and simultaneously feeding the hob in timed relation relatively across the member in a perpendiculardirection and relatively axially of the member during said rotation through cutting engagement. 7 4. The method of hobbing the end of the inside member of a spline coupling which comprises positioning the member and a longitudinally tapered hob in operative relation with thehob inclined longitudinally to the normal to the member at the thread angle and with the large end of the hob positioned for movement into engagement at full depth with the outer end of the member, rotating the member and the hob in timed relation, and feeding the hob relatively across the member in a direction diagonally of the axis of the member during said rotation to generate uniformly spaced parallel keys with tapered bases on the member. 5. The method of hobbing the end of a spline shaft with longitudinal uniformly spaced parallel integral keys having tapered bases concentric with the axis of the shaft which comprises positioning a hob tapered from' one end to the other and with the "tops to the section, and,

of the hob teeth inclined laterally axially of the hob, relatively in operative relation to the shaft, with the hob inclined longitu- (linally to the normal to the shaft at an angle corresponding to the thread angle and positioned with the large end off the end and at one side of the shaft, rotating the shaft and the hob in timed relation, and

feeding the hob simultaneously longitudinally of the shaft and perpendicularly across the shaft during said rotation through cutting engagement.

6. The method of bobbing a rotary member which comprises positioning the member and a multiple-thread hob in operative relation, with the hob inclined longitudinall to the member, and'initially located off the end and at one side of the member, rotating the member and lation, and feeding the hobrelatively across the member in a direction inclined to the gob axis diagonally of the axis of the mem- 7. The method of hobbing a tapered spline shaft which comprises positioning the shaft and a longitudinally tapered single-thread hob in foperative relation, with the hob inclined longitudinally to the normal to the shaft at the thread angle and with the large end ofthe hob positioned for movement into engagement at full depth with the outer end of said shaft, the hob having a cylindrical body, a thread decreasing in height from one end to the other, and teeth with their tops inclined axially of the body, rotating the shaft and the hob in timed relation, and feeding the hob relatively across the shaft in a diagonal direction inclined to the hob axis during said rotation to generate uniformly spaced integral keys with longitudinally ta red and laterally arcuate bases on the sha -8. The method of hobbing a spline shaft section comprising providing a hob having a longitudinally tapered thread intersected by gashes to define helically aligned teeth, the teeth having clearance lugs along the side margins of their tops, positioning the hob at a longitudinal angle to said section, rotating the section and the hob in timed relation, and. moving the hob relatively across the axis of the section along a diagonal line at an angle to the hob axis during said rotation through cutting engagement.

9. The method of hobbing the cylindrical inside member of a spline coupling with longitudinal uniformly spaced parallel integral keys having tapered bases concentric in lateral curvature with the axis of the member which comprises providing a hob having a tooth thread tapered in height from one end to the other with the tops of the hob teeth inclined laterally axially of the hob, and having clearance lugs along the side margins of the tops of the teeth, said the hob in timed relugs being uniform in width throu houtthe length of the hob, positioning'the ob at a longitudinal angle to the normal to the member corresponding to the helix angle and initially with the large end off the end and at one side of themember, rotating themember and the hob in timed relation, and feeding the hob simultaneously across the 1, member in a direction inclined to the hob axis and extending diagonally of the member axis, during said rotation through cutting engagement. 10. The method of hobbing the inside member of a spline coupling. with elongated generally longitudinal laterally alined peripheral projections of a predetermined length, the projections being separated by elongated spaces having root surfaces concentric in form about the axis of rotation, said method comprising providing a hob having a predetermined longitudinal contour, rotating the hob, relatively feeding the hob in arectilinear path extending diagonally across said axis and at angle to the hob axis through cutting engagement with the member, the hob being longitudinally inclined from a perpendicular to said axis at an angle corresponding to its lead angle, the hob section having an effective length such' that the projection of its: axis along said path on an axial plane of the member is coextensive in length and position with the projections to be cut, and during said engagement rotating the member in timed 3 relation to the rotation of the hob and the feeding movement relative thereto.

11. The method of bobbing the cylindrical inside member of a spline coupling with elongated generally longitudinal laterally alined peripheral'projections of a predetermined length, which comprises rotating a hob, relatively feeding saidv hob in a path extending at an angle to the hob axis and diagonal y across the axis of rotation of the member through cutting engagement therewith, the hob bet'ng longitudinally inclined to said path and having a section with an effective length such that the projection of the axis of the section along said path on an axial plane of the member is coextensive in length and position with the projections to be, cut, and during said engagement rotating the member in timed relation to the rotation of the hob and the feeding movement v relative thereto. a I

In testimony whereof, I have hereunto afiixed my signature.

. JOHN EDGAR. 

